Find the area of a triangle PQR

Question

Find the area of a triangle PQR, where P=(5,5,-5),Q=(5,0,5) and R=(-2,-3,3)

Answer 1

There is a formula for the area of a triangle given its co-ordinates using a determinant:

|x₁ y₁ 1|

.5 |x₂ y₂ 1|

|x₃ y₃ 1|

I have written the determinant as clearly as I can given the limitations of this editor.

Alternatively you can use the distance formula to find the length of each side and then use Heron's formula.